    body {
    width:100%; /* body的宽度与浏览器保持一致*/
    margin: 0 auto; /* 页面最大宽度是640px，如果在比较大的手机上显示，显示不完全，居中显示 */
    min-width: 320px;  /* 目前市面上最小手机分辨率为320 */
    max-width: 640px;  /*经过测量*/
    background: #fff;
    font-size: 14px;
    font-family: -apple-system, Helvetica, sans-serif;
    line-height: 1.5;
    color: #666;
    }
    img {
        vertical-align: middle;
    }
    a {
        text-decoration: none;
        color: #666;
    }

    /* <!-- 顶部 开始 --> */
    .app ul {
        margin: 0;
        padding: 0;
        text-align: center;
        line-height: 45px;
        height: 45px;
    }
    .app ul li {
        float: left;
        list-style: none;
        background-color: #232326;
        font-size: 14px;
        color: #fff;
    }
    .app ul li:nth-child(1) {
        width: 8%;
    }
    .app ul li:nth-child(1) img {
        width: 10px;
    }
    .app ul li:nth-child(2) {
        width: 10%;
    }
    .app ul li:nth-child(2) img {
        width: 30px;
        vertical-align: middle;
        /* 图片和文字居中对齐 */
    }
    .app ul li:nth-child(3) {
        width: 57%;
    }
    .app ul li:nth-child(4) {
        width: 25%;
        background-color: #f63515;
    }
    /* <!-- 顶部 结束 --> */

    /* 搜索 开始 */
    .search-wrap {
        position: fixed;
        /* 固定定位 */
        width: 100%;
        /* 固定定位必须加宽 */
        height: 44px;
        overflow: hidden;
        min-width: 320px;
        max-width: 640px;
    }
    .search-left {
        position: absolute;
        left: 0;
        top: 0;
        height: 44px;
        width: 40px;
    }
    .search-left::before {
        content: "";
        display: block;
        width: 20px;
        height: 18px;
        background: url(../images/s-btn.png)no-repeat;
        background-size: 20px 18px;
        margin: 13px 0 0 15px;
    }
    .search {
        position: relative;
        height: 30px;
        background-color: #fff;
        margin: 0 50px;
        border-radius: 20px;
        margin-top: 7px;
    }
    .search-icon {
        position: absolute;
        top: 8px;
        left: 12px;
        background: url(../images/jd.png)no-repeat;
        background-size: 20px 15px;
        width: 20px;
        height: 15px;
    }
    .search-sousuo {
        position: absolute;
        top: 9px;
        left: 45px;
        width: 18px;
        height: 15px;
        background: url(../images/jd-sprites.png)no-repeat -83px 0;
        background-size: 200px auto;
    }
    .search-icon::after {
        position: absolute;
        top: 0;
        right: -8px;
        content:"";
        border-right: 1px solid #ccc;
        /* width: 1px; */
        height: 15px;
    }
    .search-right {
        position: absolute;
        top: 0;
        right: 0;
        height: 44px;
        width: 40px;
        color: #fff;
        line-height: 44px;
    }
    /* 搜索 结束 */

    /* 主体部分 开始 */
    .slider img {
        width: 100%;
    }
    .brand {
        overflow: hidden;
        /* 解决溢出隐藏、清除浮动、外边距塌陷 */
    }
    .brand div {
        float: left;
        width: 33.33%;
    }
    .brand div img {
        width: 100%;
    }
    .nav {
        margin: 10px 0;
    }
    .nav a {
        float: left;
        width: 20%;
        display: block;
        text-align: center;
    }
    .nav a img {
        width: 40px;
        height: 40px;
    }
    .nav a p {
        margin-top: 8px;
    }
    .news a {
        float: left;
        box-sizing: border-box;
        /* 使边框宽度和padding值全部算在最初给的宽度里面 */
    }
    
    .news a:nth-child(1) {
        width: 50%;
    }
    .news a:nth-child(n+2) {
        width: 25%;
        border-left: 1px solid #ccc;
    }
    .news img {
        width: 100%;
    }
